1. Field of the Invention
The present invention relates to a laminated ceramic package, and more particularly, to a laminated ceramic package capable of precisely adjusting the dimensions of a cavity mounted with electronic components by suppressing a firing shrinkage in the cavity.
2. Description of the Related Art
Recently, the miniaturization of circuit components is increasingly being required in the technical field of a mobile communication device such as a cellular phone. Also, technologies of embedding devices such as a capacitance device and an inductance device in a ceramic body using Low Temperature Co-fired Ceramics (LTCC) have been introduced.
In a laminated ceramic package using a ceramic laminated substrate, a cavity is formed in the laminated ceramic package. Then, the electronic components may be mounted on the ceramic laminated substrate in the cavity, and fixed on a substrate through a molding process.
When the cavity is formed on the ceramic laminated substrate, there is a limitation in securing the dimensional accuracy of the cavity. Generally, in order to manufacture a ceramic package, the following processes are performed. First, a plurality of green sheets are laminated to form a laminated body. A cavity capable of receiving chips is formed by removing a partial section of the laminated body through punching or laser processing. Then, the ceramic package is formed through a non-shrinkage firing process by positioning the laminated body between constraint layers. The inner part of the cavity is divided into a region for mounting the electronic components and a region for a wire-bonding, and formed in a stepped shape.
In order to prevent a horizontal (X or Y-axis) directional shrinkage and allow a vertical (Z-axis) directional shrinkage during firing, the non-shrinkage firing process may include forming the constraint layers formed of a material, which may not be fired at a firing temperature of the laminated body, on the upper and lower surfaces of the laminated body, and pressing the laminated body during the firing process.
However, when the cavity is formed on the laminated body in order to implement the ceramic package having the cavity receiving the electronic components, the constraint layer for pressing the laminated body may not be in substantial contact with the laminated body at the inner part of the cavity. Accordingly, during firing, the horizontal shrinkage of a green sheet of a region contacting the constraint layer is suppressed, but the horizontal shrinkage of a green sheet of a region not contacting the constraint layer is not suppressed, so that a accuracy difference between the both green sheets may occur.